Vom Berg and Hahn–Eyring Drilling Fluid Rheological Models

This article presents rheological models of fluids used in the drilling practice. It discusses the principles of determining drilling fluid rheological parameters based on data acquired from measurements by means of viscometers used in the drilling practice. The authors propose the application of the three-parameter Vom Berg and Hahn–Eyring models not used in the drilling industry so far. Necessary relationships have been developed for these models, which enable the determination of rheological parameters. In order to account for the influence of different flow conditions on the value of drilling fluid rheological parameters, the approach proposing the determination of rheological parameters of a given three-parameter model separately for low shear rates and high shear rates has been suggested. A practical application of the methodology proposed in this paper for determining the rheological parameters of the three-parameter Vom Berg and Hahn–Eyring models is presented using real drilling fluids as an example. Using the author’s methodology for determining the optimum rheological model, called Rheosolution, described earlier in the paper “Selection of Suitable Rheological Model for Drilling Fluid Using Applied Numerical Methods”, published in Energies 2020, 13, 3192, and laboratory tests performed for this work (for cement slurries according to API standards), a strong correlation of the Vom Berg model and, in particular, the Hahn–Eyring model for such drilling fluids was demonstrated.